1. Field of the Invention
This invention relates to the field of art of electronic test head positioners.
2. Background Art
In the automatic testing of integrated circuits (IC) and other electronic devices, special device handlers have been used which place the device to be tested in position. The electronic testing itself is provided by a large and expensive automatic testing system which includes a test head which has been required to connect to and dock with the device handler. In such testing systems, the test head has been usually very heavy in the order of 75 to 300 pounds. The reason for this heaviness is that the test head uses high speed electronic timing signals so that the electronic circuits must be located as close as possible to the device under test. Accordingly, the test head has been densely packaged with electronic circuits in order to achieve the high speed testing of the sophisticated devices.
The prior art has left much to be desired in providing a manipulator or positioner to easily move the heavy test head accurately into position with respect to the device handler mechanism. In some prior positioners the test head has been positioned by means of lead screws and rotating and sliding mechanisms each movable one at a time. These prior systems left much to be desired in that they did not provide all of the degrees of freedom necessary for easy and accurate docking with the handler. The user has had to move the heavy device handler or the heavy positioner itself in order to provide alignment. Other prior art manipulating systems have used motors to drive the lead screws in the up/down direction. Such a motor driven lead screw or even a hand driven one provides the possibility of damaging either the test head socket connections or the connections which are on the device handler due to overstressing.
Another disadvantage of the prior art systems is that they are large and take up a considerable amount of floor space which is at a premium in test facilities. A further difficulty of large prior systems has involved the cable which connects the test system to the test head which is usually short, cumbersome and fragile. Accordingly as a result of their size and construction, prior systems could not be moved sufficiently close to the test system.
For purposes of considering patentability, a brief patentability search was conducted. The patents identified to be of possible interest in the search were:
______________________________________ Patent No. Inventor ______________________________________ 4,199,294 Streck et al. 4,062,455 Carl Flatau 4,132,318 Wang et al. 3,873,148 Robert Kennicuit 4,076,131 Dahlstrom et al. 4,188,166 Moreau et al. 4,273,506 Thomson et al. 4,299,529 Inaba et al. 4,264,266 Hans Trechsel 3,791,052 Cornelis Van Der Lely 3,826,383 Hans Richter 4,303,368 Dent et al. ______________________________________
Accordingly, an object of the present invention is an electronic test head positioner that has six degrees of freedom and provides a substantially weightless condition to the test head which may be manipulated by hand for easy and accurate docking and undocking of the test head with the device handler.
Another object of the invention is an electronic test head positioner formed by a column rising vertically from a base which takes little room on the floor with respect to the test system.